In modern medical practice small tissue samples, known as biopsy specimens, are often removed from tumors, lesions, organs, muscles and other tissues of the body. The removal of tissue samples may be accomplished by open surgical technique, or through the use of a specialized biopsy instrument such as a biopsy needle, including vacuum assisted biopsy devices.
After a tissue sample has been removed, it is typically subjected to diagnostic tests or examinations to determine cytology, histology, presence or absence of chemical substances that act as indicators for disease states, or the presence of bacteria or other microbes. The above mentioned and other diagnostic tests and examinations per se are well known in the art and need not be described here. As is known, obtaining a tissue sample by biopsy and the subsequent examination are frequently employed in the diagnosis of cancers and other malignant tumors or to confirm that a suspected lesion or tumor is not malignant, and are frequently used to devise a plan for the appropriate surgical procedure or other course of treatment.
Examination of tissue samples taken by biopsy is of particular significance in the diagnosis and treatment of breast cancer, the most common cancer suffered by women throughout the world. Proper diagnostic procedures, frequent examination by well known techniques such as “mammography” and prompt subsequent surgical treatment have, however, significantly reduced the mortality rate caused by this form of cancer. For this reason, references in the background and description of embodiments are made to marking biopsy sites in human and other mammalian breasts, although the invention is suitable for marking biopsy sites in other parts of the human and other mammalian body as well.
Thus, as is known, when an abnormal mass in the breast is found by physical examination or mammography, a biopsy procedure follows. A biopsy procedure can include an open surgical biopsy or a technique such as Fine Needle Aspiration Biopsy (FNAB) or less invasive stereotactic needle biopsy.
Oftentimes, in connection with biopsy procedures, the radiologist or surgeon feels a marker should be used to mark the site of the biopsy for later reference. Such markers can be formed of surgical alloys such as titanium alloys, including shape memory alloys. It is generally important that the marker be capable of being imaged by an imaging modality, such as magnetic resonance imaging (MRI), ultrasound, and/or X-ray. Placement of a marker can be an important step to take since most abnormalities biopsied are small or subtle and can become extremely difficult or impossible to identify after a core biopsy procedure. When a biopsy result is abnormal and an excision or lumpectomy is necessary, the marker allows accurate localization of the abnormal site for removal so that as little tissue as necessary is removed while optimizing the chance of clear margins.
Most patients have normal (benign) results from these types of biopsy, however, the presence of the marker is helpful when seen on follow-up mammograms; it shows exactly where the area was biopsied. This avoids confusion in interpretation of follow-up mammograms and can prevent the need for future biopsies in that same area.
Despite successful use of various marker structures, a need in the art continues to exist for biopsy site markers that resist migration from the deployed location, such as the biopsy cavity created as a result of the biopsy procedure, even when the breast tissue is moved, manipulated or decompressed. Moreover, such desired markers should remain detectable at the biopsy site by one of the above-mentioned modalities.